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[PATCH v3 3/3] Change force_parallel_mode to a DEVELOPER GUC, and remove it from sample config.. 181+ 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 <[email protected]> 0 siblings, 0 replies; 181+ 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] 181+ 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 <[email protected]> 0 siblings, 0 replies; 181+ 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] 181+ 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 <[email protected]> 0 siblings, 0 replies; 181+ 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] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v8] using indexscan to speedup add not null constraints @ 2025-10-20 05:29 jian he <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: jian he @ 2025-10-20 05:29 UTC (permalink / raw) This patch tries to use index_beginscan() / index_getnext() / index_endscan() mentioned in [1] to speedup adding not-null constraints to the existing table. The main logic happens in phase3 ATRewriteTable 1. collect all not-null constraints. 2. For each not-null constraint, check whether there is a corresponding index available for validation. If not, then can not use indexscan to verify not-null constraints. 3. If any of the following conditions are true * table scan or rewrite is required, * table wasn't locked with `AccessExclusiveLock` * the NOT NULL constraint applies to a virtual generated column then index scan cannot be used for fast validation. 4. If all conditions are satisfied, attempt to use indexscan to verify whether the column contains any NULL values. concurrency concern: ALTER TABLE SET NOT NULL will take an ACCESS EXCLUSIVE lock, so there is less variant of racing issue can occur? to prove accurate, I wrote some isolation tests. see[2] performance: demo: case when: %20 percent values are NULL and have been deleted from heap but they still on the index. drop table if exists t; create unlogged table t(a int, b int) with (autovacuum_enabled = off, vacuum_index_cleanup=off); insert into t select case when g % 5 = 0 then null else g end, g+1 from generate_series(1,1_000_000) g; create index t_idx_a on t(a); delete from t where a is null; alter table t alter column a drop not null; alter table t add constraint t1 not null a; the above two statement running several times: patch Time:: 1.084 ms master Time: 12.045 ms references: [1] https://postgr.es/m/CA%2BTgmoa5NKz8iGW_9v7wz%3D-%2BzQFu%3DE4SZoaTaU1znLaEXRYp-Q%40mail.gmail.com [2] https://postgr.es/m/900056D1-32DF-4927-8251-3E0C0DC407FD%40anarazel.de discussion: https://postgr.es/m/CACJufxFiW=4k1is=F1J=r-Cx1RuByXQPUrWB331U47rSnGz+hw@mail.gmail.com commitfest entry: https://commitfest.postgresql.org/patch/5444 --- src/backend/commands/tablecmds.c | 116 +++++++++- src/backend/executor/execIndexing.c | 213 ++++++++++++++++++ src/include/executor/executor.h | 2 + .../expected/indexscan-check-notnull.out | 97 ++++++++ src/test/isolation/isolation_schedule | 1 + .../specs/indexscan-check-notnull.spec | 45 ++++ src/test/modules/test_misc/meson.build | 1 + .../t/011_indexscan_validate_notnull.pl | 163 ++++++++++++++ 8 files changed, 632 insertions(+), 6 deletions(-) create mode 100644 src/test/isolation/expected/indexscan-check-notnull.out create mode 100644 src/test/isolation/specs/indexscan-check-notnull.spec create mode 100644 src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c index f976c0e5c7e..2af06630b35 100644 --- a/src/backend/commands/tablecmds.c +++ b/src/backend/commands/tablecmds.c @@ -210,16 +210,19 @@ typedef struct AlteredTableInfo List *changedStatisticsDefs; /* string definitions of same */ } AlteredTableInfo; -/* Struct describing one new constraint to check in Phase 3 scan */ -/* Note: new not-null constraints are handled elsewhere */ +/* + * Struct describing one new constraint to check in Phase 3 scan. Note: new + * not-null constraints are handled here too. +*/ typedef struct NewConstraint { char *name; /* Constraint name, or NULL if none */ - ConstrType contype; /* CHECK or FOREIGN */ + ConstrType contype; /* CHECK or FOREIGN or NOT NULL */ Oid refrelid; /* PK rel, if FOREIGN */ Oid refindid; /* OID of PK's index, if FOREIGN */ bool conwithperiod; /* Whether the new FOREIGN KEY uses PERIOD */ Oid conid; /* OID of pg_constraint entry, if FOREIGN */ + int attnum; /* NOT NULL constraint attribute number */ Node *qual; /* Check expr or CONSTR_FOREIGN Constraint */ ExprState *qualstate; /* Execution state for CHECK expr */ } NewConstraint; @@ -6217,6 +6220,9 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) needscan = true; con->qualstate = ExecPrepareExpr((Expr *) expand_generated_columns_in_expr(con->qual, oldrel, 1), estate); break; + case CONSTR_NOTNULL: + /* Nothing to do here */ + break; case CONSTR_FOREIGN: /* Nothing to do here */ break; @@ -6270,10 +6276,69 @@ ATRewriteTable(AlteredTableInfo *tab, Oid OIDNewHeap) wholeatt->attnum); } } - if (notnull_attrs || notnull_virtual_attrs) - needscan = true; } + /*- + * If we have to verify new not-null constraints and don't have any other + * reason to fully scan the table, then we can use indexes to test for + * absence of NULL values instead of scanning. The following conditions + * must be met: + * - we're operating on a regular table + * - we hold AccessExclusiveLock on the table + * - no not-null constraint covers a virtual generated column, + * because no indexes can be created on them + */ + if (!needscan && + newrel == NULL && + tab->verify_new_notnull && + notnull_virtual_attrs == NIL && + oldrel->rd_rel->relkind == RELKIND_RELATION && + CheckRelationLockedByMe(oldrel, AccessExclusiveLock, false)) + { + List *notnull_attnums = NIL; + + Assert(!tab->rewrite); + + foreach(l, tab->constraints) + { + Form_pg_attribute attr; + NewConstraint *con = lfirst(l); + + if (con->contype != CONSTR_NOTNULL) + continue; + + attr = TupleDescAttr(newTupDesc, con->attnum - 1); + + Assert(attr->attnotnull); + Assert(attr->attnum == con->attnum); + + if (attr->attgenerated == ATTRIBUTE_GENERATED_VIRTUAL) + { + needscan = true; + break; + } + + notnull_attnums = lappend_int(notnull_attnums, attr->attnum); + } + + /* + * Validate new NOT NULL constraints, unless we need a scan for other + * reasons, because we can validate them cheaply there, and doing it + * also here would be a waste of cycles. + */ + if (notnull_attnums != NIL && !needscan) + { + if (!index_check_notnull(oldrel, notnull_attnums)) + needscan = true; + else + ereport(DEBUG1, + errmsg_internal("all new not-null constraints on relation \"%s\" have been validated by using index scan", + RelationGetRelationName(oldrel))); + } + } + else if (notnull_attrs || notnull_virtual_attrs) + needscan = true; + if (newrel || needscan) { ExprContext *econtext; @@ -7949,6 +8014,7 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, CookedConstraint *ccon; List *cooked; bool is_no_inherit = false; + AlteredTableInfo *tab = NULL; /* Guard against stack overflow due to overly deep inheritance tree. */ check_stack_depth(); @@ -8073,10 +8139,32 @@ ATExecSetNotNull(List **wqueue, Relation rel, char *conName, char *colName, constraint->is_no_inherit = is_no_inherit; constraint->conname = conName; + tab = ATGetQueueEntry(wqueue, rel); + /* and do it */ cooked = AddRelationNewConstraints(rel, NIL, list_make1(constraint), false, !recursing, false, NULL); ccon = linitial(cooked); + + Assert(ccon->contype == CONSTR_NOTNULL); + + /* + * We may use indexscan to vertify not-null constraint in Phase3. Add the + * to-be-validated not-null constraint to Phase 3's queue. + */ + if (!ccon->skip_validation) + { + NewConstraint *newcon; + + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + + newcon->name = ccon->name; + newcon->contype = ccon->contype; + newcon->attnum = ccon->attnum; + + tab->constraints = lappend(tab->constraints, newcon); + } + ObjectAddressSet(address, ConstraintRelationId, ccon->conoid); InvokeObjectPostAlterHook(RelationRelationId, @@ -9983,13 +10071,15 @@ ATAddCheckNNConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel, { CookedConstraint *ccon = (CookedConstraint *) lfirst(lcon); - if (!ccon->skip_validation && ccon->contype != CONSTR_NOTNULL) + if (!ccon->skip_validation) { NewConstraint *newcon; newcon = palloc0_object(NewConstraint); newcon->name = ccon->name; newcon->contype = ccon->contype; + if (ccon->contype == CONSTR_NOTNULL) + newcon->attnum = ccon->attnum; newcon->qual = ccon->expr; tab->constraints = lappend(tab->constraints, newcon); @@ -13258,6 +13348,7 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, List *children = NIL; AttrNumber attnum; char *colname; + NewConstraint *newcon; con = (Form_pg_constraint) GETSTRUCT(contuple); Assert(con->contype == CONSTRAINT_NOTNULL); @@ -13321,7 +13412,20 @@ QueueNNConstraintValidation(List **wqueue, Relation conrel, Relation rel, /* Set attnotnull appropriately without queueing another validation */ set_attnotnull(NULL, rel, attnum, true, false); + /* + * Queue validation for phase 3. + * + * ALTER TABLE SET NOT NULL will add NOT NULL constraint to + * AlteredTableInfo->constraints, for consistency, do the same here. + */ + newcon = (NewConstraint *) palloc0(sizeof(NewConstraint)); + newcon->name = colname; + newcon->contype = CONSTR_NOTNULL; + newcon->attnum = attnum; + + /* Find or create work queue entry for this table */ tab = ATGetQueueEntry(wqueue, rel); + tab->constraints = lappend(tab->constraints, newcon); tab->verify_new_notnull = true; /* diff --git a/src/backend/executor/execIndexing.c b/src/backend/executor/execIndexing.c index 6ae0f959592..88694ce0335 100644 --- a/src/backend/executor/execIndexing.c +++ b/src/backend/executor/execIndexing.c @@ -108,12 +108,15 @@ #include "access/genam.h" #include "access/relscan.h" +#include "access/table.h" #include "access/tableam.h" #include "access/xact.h" #include "catalog/index.h" +#include "catalog/pg_am_d.h" #include "executor/executor.h" #include "nodes/nodeFuncs.h" #include "storage/lmgr.h" +#include "utils/fmgroids.h" #include "utils/injection_point.h" #include "utils/multirangetypes.h" #include "utils/rangetypes.h" @@ -146,6 +149,7 @@ static bool index_expression_changed_walker(Node *node, Bitmapset *allUpdatedCols); static void ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char typtype, Oid atttypid); +static bool index_check_notnull_internal(Relation relation, List *attnums, List *idxs); /* ---------------------------------------------------------------- * ExecOpenIndices @@ -1178,3 +1182,212 @@ ExecWithoutOverlapsNotEmpty(Relation rel, NameData attname, Datum attval, char t errmsg("empty WITHOUT OVERLAPS value found in column \"%s\" in relation \"%s\"", NameStr(attname), RelationGetRelationName(rel)))); } + +/* + * notnull_attnums: list of attribute numbers of all new not-null constraints. + * + * First check whether the relation has a suitable index for each not-null + * attribute, then using indexscan mechanism to verify that *all* attributes on + * notnull_attnums are indeed not null. + * + * Returning true means all new not-null constraints have been verified, no + * need an extra scan to verify newly added not-null constraints. + */ +bool +index_check_notnull(Relation relation, List *notnull_attnums) +{ + Relation pg_index; + Relation index_rel; + SysScanDesc indscan; + ScanKeyData skey; + HeapTuple htup; + TupleDesc tupdesc; + Form_pg_attribute attr; + List *idxs = NIL; + List *attnums = NIL; + + tupdesc = RelationGetDescr(relation); + + /* Prepare to scan pg_index for entries having indrelid = this rel */ + ScanKeyInit(&skey, + Anum_pg_index_indrelid, + BTEqualStrategyNumber, F_OIDEQ, + ObjectIdGetDatum(RelationGetRelid(relation))); + + pg_index = table_open(IndexRelationId, AccessShareLock); + indscan = systable_beginscan(pg_index, IndexIndrelidIndexId, true, + NULL, 1, &skey); + + while (HeapTupleIsValid(htup = systable_getnext(indscan))) + { + Form_pg_index index = (Form_pg_index) GETSTRUCT(htup); + + /* + * we can only use non-deferred, validated, and alive btree index to + * validate not-null constraints + */ + if (!index->indimmediate || !index->indisvalid || !index->indislive) + continue; + + /* can not use expression index or partial index too */ + if (!heap_attisnull(htup, Anum_pg_index_indexprs, NULL) || + !heap_attisnull(htup, Anum_pg_index_indpred, NULL)) + continue; + + index_rel = index_open(index->indexrelid, AccessShareLock); + + /* can only apply to btree index */ + if (index_rel->rd_rel->relam != BTREE_AM_OID) + { + index_close(index_rel, AccessShareLock); + continue; + } + + /* collect index attnums while loop */ + for (int i = 0; i < index->indnkeyatts; i++) + { + attr = TupleDescAttr(tupdesc, (index->indkey.values[i] - 1)); + + if (attr->attisdropped) + continue; + + if (list_member_int(notnull_attnums, attr->attnum) && + !list_member_int(attnums, attr->attnum)) + { + attnums = lappend_int(attnums, attr->attnum); + idxs = lappend_oid(idxs, index->indexrelid); + } + } + index_close(index_rel, NoLock); + } + systable_endscan(indscan); + table_close(pg_index, AccessShareLock); + + if (attnums == NIL) + return false; + + /* + * every not-null constraint requires an index for indexscan. If no such + * index exists, we need to use regular table scan to validate not-null + * constraints. + */ + foreach_int(attno, notnull_attnums) + { + if (!list_member_int(attnums, attno)) + return false; + } + + return index_check_notnull_internal(relation, attnums, idxs); +} + +/* + * Use indexscan mechanism to fast verify each attribute in "attnums" are + * not-null or not. + */ +static bool +index_check_notnull_internal(Relation relation, List *attnums, List *idxs) +{ + EState *estate; + ExprContext *econtext; + TupleTableSlot *existing_slot; + bool all_not_null = true; + ListCell *lc, + *lc2; + + /* + * Need an EState for slot to hold the current tuple. + */ + estate = CreateExecutorState(); + econtext = GetPerTupleExprContext(estate); + + forboth(lc, attnums, lc2, idxs) + { + SnapshotData DirtySnapshot; + IndexScanDesc index_scan; + ScanKeyData scankeys[INDEX_MAX_KEYS]; + IndexInfo *indexInfo; + AttrNumber sk_attno = -1; + Relation index; + int indnkeyatts; + + AttrNumber attno = lfirst_int(lc); + Oid indexoid = lfirst_oid(lc2); + + existing_slot = table_slot_create(relation, NULL); + + /* Arrange for econtext's scan tuple to be the tuple under test */ + econtext->ecxt_scantuple = existing_slot; + + index = index_open(indexoid, NoLock); + + indexInfo = BuildIndexInfo(index); + indnkeyatts = IndexRelationGetNumberOfKeyAttributes(index); + + /* + * Search the tuples that are in the index for any violations, + * including tuples that aren't visible yet. + */ + InitDirtySnapshot(DirtySnapshot); + + for (int i = 0; i < indnkeyatts; i++) + { + if (indexInfo->ii_IndexAttrNumbers[i] == attno) + { + sk_attno = i + 1; + break; + } + } + + if (sk_attno == -1) + elog(ERROR, "cache lookup failed for attribute number %d on index %u", indexoid, attno); + + for (int i = 0; i < indnkeyatts; i++) + { + /* set up an IS NULL scan key so that we ignore not nulls */ + ScanKeyEntryInitialize(&scankeys[i], + SK_ISNULL | SK_SEARCHNULL, + sk_attno, /* index col to scan */ + InvalidStrategy, /* no strategy */ + InvalidOid, /* no strategy subtype */ + InvalidOid, /* no collation */ + InvalidOid, /* no reg proc for this */ + (Datum) 0); /* constant */ + } + + index_scan = index_beginscan(relation, index, &DirtySnapshot, NULL, indnkeyatts, 0); + index_rescan(index_scan, scankeys, indnkeyatts, NULL, 0); + + while (index_getnext_slot(index_scan, ForwardScanDirection, existing_slot)) + { + Datum values[INDEX_MAX_KEYS]; + bool nulls[INDEX_MAX_KEYS]; + + /* + * Extract the index column values and isnull flags from the + * existing tuple. + */ + FormIndexDatum(indexInfo, existing_slot, estate, values, nulls); + + if (nulls[sk_attno - 1]) + { + all_not_null = false; + break; + } + } + + index_endscan(index_scan); + index_close(index, NoLock); + ExecDropSingleTupleTableSlot(existing_slot); + + /* exit earlier */ + if (!all_not_null) + { + FreeExecutorState(estate); + return false; + } + } + + FreeExecutorState(estate); + + return true; +} diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 5929aabc353..7f24caeeafb 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -756,6 +756,8 @@ extern void check_exclusion_constraint(Relation heap, Relation index, const Datum *values, const bool *isnull, EState *estate, bool newIndex); +extern bool index_check_notnull(Relation relation, List *notnull_attnums); + /* * prototypes from functions in execReplication.c */ diff --git a/src/test/isolation/expected/indexscan-check-notnull.out b/src/test/isolation/expected/indexscan-check-notnull.out new file mode 100644 index 00000000000..c6a652e2518 --- /dev/null +++ b/src/test/isolation/expected/indexscan-check-notnull.out @@ -0,0 +1,97 @@ +Parsed test spec with 2 sessions + +starting permutation: s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s1_d1: DELETE FROM t; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; <waiting ...> +step s1_c1: COMMIT; +step s2_a1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + + +starting permutation: s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +ERROR: column "a" of relation "t" contains null values +step s1_r1: ROLLBACK; +step s2_r1: ROLLBACK; + +starting permutation: s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +step s1_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s2_b2: BEGIN; +step s2_d1: DROP INDEX t_ab_idx; +step s1_d1: DELETE FROM t; <waiting ...> +step s2_r1: ROLLBACK; +step s1_d1: <... completed> +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + +step s1_r1: ROLLBACK; + +starting permutation: s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 +step s1_b2: BEGIN; +step s2_b1: BEGIN ISOLATION LEVEL REPEATABLE READ; +step s1_d1: DELETE FROM t; +step s2_d1: DROP INDEX t_ab_idx; <waiting ...> +step s1_s0: SAVEPOINT s0; +step s1_a1: ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a; +step s1_c1: COMMIT; +step s2_d1: <... completed> +step s2_c1: COMMIT; +step s1_q1: SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + +conname|conrelid|contype|convalidated +-------+--------+-------+------------ +t1_nn |t |n |t +(1 row) + diff --git a/src/test/isolation/isolation_schedule b/src/test/isolation/isolation_schedule index 01ff1c6586f..7ce6bbcaf89 100644 --- a/src/test/isolation/isolation_schedule +++ b/src/test/isolation/isolation_schedule @@ -58,6 +58,7 @@ test: merge-delete test: merge-update test: merge-match-recheck test: merge-join +test: indexscan-check-notnull test: delete-abort-savept test: delete-abort-savept-2 test: aborted-keyrevoke diff --git a/src/test/isolation/specs/indexscan-check-notnull.spec b/src/test/isolation/specs/indexscan-check-notnull.spec new file mode 100644 index 00000000000..05b4488550c --- /dev/null +++ b/src/test/isolation/specs/indexscan-check-notnull.spec @@ -0,0 +1,45 @@ + +# +# using indexscan to check a column not-null constraint +# is satisfied or not. +# + +setup +{ + CREATE TABLE t (a int, b int); + CREATE INDEX t_ab_idx on t(a,b); + INSERT INTO t values (null, 1); + INSERT INTO t SELECT x, x*10 FROM generate_series(1,3) g(x); +} + +teardown +{ + DROP TABLE t; +} + +session s1 +step s1_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s1_b2 { BEGIN; } +step s1_d1 { DELETE FROM t;} +step s1_s0 { SAVEPOINT s0;} +step s1_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s1_q1 { SELECT conname, conrelid::regclass, contype, convalidated + FROM pg_constraint WHERE conname = 't1_nn'; + } +step s1_r1 { ROLLBACK; } +step s1_c1 { COMMIT; } + +session s2 +step s2_b1 { BEGIN ISOLATION LEVEL REPEATABLE READ; } +step s2_b2 { BEGIN; } +step s2_a1 { ALTER TABLE t ADD CONSTRAINT t1_nn NOT NULL a;} +step s2_d1 { DROP INDEX t_ab_idx;} +step s2_r1 { ROLLBACK; } +step s2_c1 { COMMIT; } + +permutation s1_b1 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b2 s2_b1 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b2 s1_d1 s2_a1 s1_c1 s2_c1 s1_q1 +permutation s1_b1 s2_b1 s2_a1 s1_r1 s2_r1 +permutation s1_b1 s2_b2 s2_d1 s1_d1 s2_r1 s1_a1 s1_q1 s1_r1 +permutation s1_b2 s2_b1 s1_d1 s2_d1 s1_s0 s1_a1 s1_c1 s2_c1 s1_q1 diff --git a/src/test/modules/test_misc/meson.build b/src/test/modules/test_misc/meson.build index 6e8db1621a7..56faf359b29 100644 --- a/src/test/modules/test_misc/meson.build +++ b/src/test/modules/test_misc/meson.build @@ -19,6 +19,7 @@ tests += { 't/008_replslot_single_user.pl', 't/009_log_temp_files.pl', 't/010_index_concurrently_upsert.pl', + 't/011_indexscan_validate_notnull.pl', ], # The injection points are cluster-wide, so disable installcheck 'runningcheck': false, diff --git a/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl new file mode 100644 index 00000000000..a3f3cb409b6 --- /dev/null +++ b/src/test/modules/test_misc/t/011_indexscan_validate_notnull.pl @@ -0,0 +1,163 @@ +# Copyright (c) 2025, PostgreSQL Global Development Group + +# Verify that indexscan mechanism can speedup ALTER TABLE ADD NOT NULL + + +use strict; +use warnings FATAL => 'all'; +use PostgreSQL::Test::Cluster; +use PostgreSQL::Test::Utils; +use Test::More; + +# Initialize a test cluster +my $node = PostgreSQL::Test::Cluster->new('primary'); +$node->init(); +# Turn message level up to DEBUG1 so that we get the messages we want to see +$node->append_conf('postgresql.conf', 'client_min_messages = DEBUG1'); +$node->start; + +# Run a SQL command and return psql's stderr (including debug messages) +sub run_sql_command +{ + my $sql = shift; + my $stderr; + + $node->psql( + 'postgres', + $sql, + stderr => \$stderr, + on_error_die => 1, + on_error_stop => 1); + return $stderr; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_table_verified +{ + my $output = shift; + return index($output, 'DEBUG: verifying table') != -1; +} + +# Check whether result of run_sql_command shows that we did a verify pass +sub is_indexscan_veritify_notnull +{ + my $output = shift; + return index($output, 'DEBUG: all new not-null constraints on relation') != -1; +} + +my $output; + +note "test alter table SET NOT NULL using indexscan with partitioned table"; + +run_sql_command( + 'CREATE TABLE tp (a int, b int, c int, d int ) PARTITION BY range(a); + CREATE TABLE tpp1 partition of tp for values from ( 1 ) to (10); + CREATE TABLE tpp2 partition of tp for values from ( 10 ) to (21); + INSERT INTO tp select g, g + 10, g + 15, g + random(min=>1::int, max=>10::int) from generate_series(1,19) g; + CREATE INDEX ON tp(b); '); + +$output = run_sql_command('ALTER TABLE tp ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), + 'column b will use indexscan to verify not-null status, no need scan table'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# use indexes on partitions to fast vertifing not-null should be ok +$output = run_sql_command('ALTER TABLE tpp1 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null will not scan table'); +ok(!is_table_verified($output), 'no table scan for pp1'); +ok( $output =~ + m/all new not-null constraints on relation "tpp1" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +$output = run_sql_command('ALTER TABLE tpp2 ALTER COLUMN b SET NOT NULL;'); +ok(is_indexscan_veritify_notnull($output), 'use indexscan to validate column b not-null, will not scan table'); +ok(!is_table_verified($output), 'no table scan for tpp2'); +ok( $output =~ + m/all new not-null constraints on relation "tpp2" have been validated by using index scan/, + 'all newly added constraints proved by indexscan'); + +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL;'); + +# table rewrite then can not use indexscan to verify not-null constraint +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b SET NOT NULL, ALTER COLUMN b SET DATA TYPE bigint;' +); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'table tp will rewrite, can not use indexscan to verify not-null constraints on it'); + +# test using indexscan with multiple not-null constraints +run_sql_command( + 'ALTER TABLE tp ALTER COLUMN b DROP NOT NULL; + CREATE INDEX ON tp(c); + CREATE INDEX ON tp(d); '); + +# one column can use indexscan, another can not, so can not use indexscan to verify not-null +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN a SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c'); +ok(is_table_verified($output), 'table scan for tp'); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to verify not-null constraints on table tp'); + +# all columns have index on it +# use indexscan to verify multiple not-null constraints should just fine +$output = run_sql_command( + 'ALTER TABLE tp ALTER COLUMN d SET NOT NULL, ADD CONSTRAINT c_nn NOT NULL c, ALTER COLUMN b SET NOT NULL;'); +ok(!is_table_verified($output), 'no table scan for tp'); +ok(is_indexscan_veritify_notnull($output), + 'using indexscan to verify not-null constraints on column b, c, d, no need table scan'); + +# test with non-partitioned table and other non-Btree index. +run_sql_command( + 'CREATE TABLE t1(f1 INT, f2 int, f3 int,f4 int, f5 int); + INSERT INTO t1 select g, g+1, g+2, g+3, g+4 from generate_series(1, 100) g; + CREATE INDEX t1_f1_f2_idx ON t1(f1,f2); + CREATE UNIQUE INDEX t1_f3idx ON t1(f3); + CREATE INDEX t1_f3f4idx ON t1(f3) include(f4); + CREATE INDEX hash_f5_idx ON t1 USING hash (f5 int4_ops); '); + +# ALTER TABLE VALIDATE CONSTRAINT can not use indexscan, +# because it only hold ShareUpdateExclusiveLock lock. +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn_t1_f2 NOT NULL f2 NOT VALID;'); + +$output = run_sql_command( + 'ALTER TABLE t1 VALIDATE CONSTRAINT nn_t1_f2;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan for ALTER TABLE VALIDATE CONSTRAINT command'); +run_sql_command('ALTER TABLE t1 DROP CONSTRAINT nn_t1_f2;'); + +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f1 SET NOT NULL, ALTER f1 type bigint;' +); +ok(!is_indexscan_veritify_notnull($output), 'table t1 will rewrite, can not use indexscan to validate not-null constraints on t1'); + +run_sql_command('ALTER TABLE t1 ALTER COLUMN f1 DROP NOT NULL;'); +run_sql_command('ALTER TABLE t1 ADD CONSTRAINT nn NOT NULL f1, ALTER f1 type bigint;'); + +# can use indexscan mechanism to fast add multiple not-null constraints +$output = run_sql_command( + 'ALTER TABLE t1 ALTER COLUMN f2 SET NOT NULL, ALTER COLUMN f1 SET NOT NULL;' +); +ok( $output =~ + m/all new not-null constraints on relation "t1" have been validated by using index scan/, + 'all not-null constraints are validated by indexscan'); + +# using indexscan mechanism to fast add a not-null can only apply to key columns, not include column +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nnf4 NOT NULL f4;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraint on t1'); + +# if index is not btree index then cannot use indexscan mechanism to fast add not-null constraint +$output = run_sql_command( + 'ALTER TABLE t1 ADD CONSTRAINT nn_f5 NOT NULL f5;' +); +ok(!is_indexscan_veritify_notnull($output), 'can not use indexscan to validate not-null constraints on t1'); + +$node->stop('fast'); + +done_testing(); -- 2.47.3 --xpkr6zhfzd3fjt76-- ^ permalink raw reply [nested|flat] 181+ messages in thread
* [PATCH v3 4/4] run pgindent @ 2026-05-06 21:43 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 181+ messages in thread From: Nathan Bossart @ 2026-05-06 21:43 UTC (permalink / raw) --- src/bin/pg_dump/pg_dump.c | 457 ++++++++++++------------ src/bin/pg_dump/pg_dumpall.c | 30 +- src/bin/pg_upgrade/check.c | 16 +- src/bin/pg_upgrade/exec.c | 8 +- src/bin/pg_upgrade/multixact_rewrite.c | 80 ++--- src/bin/pg_upgrade/pg_upgrade.c | 2 +- src/bin/pg_upgrade/relfilenumber.c | 54 +-- src/bin/psql/command.c | 29 +- src/bin/psql/describe.c | 461 ++++++++++++------------- 9 files changed, 567 insertions(+), 570 deletions(-) diff --git a/src/bin/pg_dump/pg_dump.c b/src/bin/pg_dump/pg_dump.c index eed9aaeb7c1..c05623b1889 100644 --- a/src/bin/pg_dump/pg_dump.c +++ b/src/bin/pg_dump/pg_dump.c @@ -1491,8 +1491,8 @@ setup_connection(Archive *AH, const char *dumpencoding, * Disable timeouts if supported. */ ExecuteSqlStatement(AH, "SET statement_timeout = 0"); - ExecuteSqlStatement(AH, "SET lock_timeout = 0"); - ExecuteSqlStatement(AH, "SET idle_in_transaction_session_timeout = 0"); + ExecuteSqlStatement(AH, "SET lock_timeout = 0"); + ExecuteSqlStatement(AH, "SET idle_in_transaction_session_timeout = 0"); if (AH->remoteVersion >= 170000) ExecuteSqlStatement(AH, "SET transaction_timeout = 0"); @@ -1505,10 +1505,10 @@ setup_connection(Archive *AH, const char *dumpencoding, /* * Adjust row-security mode, if supported. */ - if (dopt->enable_row_security) - ExecuteSqlStatement(AH, "SET row_security = on"); - else - ExecuteSqlStatement(AH, "SET row_security = off"); + if (dopt->enable_row_security) + ExecuteSqlStatement(AH, "SET row_security = on"); + else + ExecuteSqlStatement(AH, "SET row_security = off"); /* * For security reasons, we restrict the expansion of non-system views and @@ -1955,7 +1955,7 @@ checkExtensionMembership(DumpableObject *dobj, Archive *fout) if (fout->dopt->binary_upgrade) dobj->dump = ext->dobj.dump; else - dobj->dump = ext->dobj.dump_contains & (DUMP_COMPONENT_ACL); + dobj->dump = ext->dobj.dump_contains & (DUMP_COMPONENT_ACL); return true; } @@ -1989,9 +1989,9 @@ selectDumpableNamespace(NamespaceInfo *nsinfo, Archive *fout) else if (strcmp(nsinfo->dobj.name, "pg_catalog") == 0) { /* - * We dump out any ACLs defined in pg_catalog, if - * they are interesting (and not the original ACLs which were set at - * initdb time, see pg_init_privs). + * We dump out any ACLs defined in pg_catalog, if they are interesting + * (and not the original ACLs which were set at initdb time, see + * pg_init_privs). */ nsinfo->dobj.dump_contains = nsinfo->dobj.dump = DUMP_COMPONENT_ACL; } @@ -3298,7 +3298,7 @@ dumpDatabase(Archive *fout) "datcollate, datctype, datfrozenxid, " "datacl, acldefault('d', datdba) AS acldefault, " "datistemplate, datconnlimit, "); - appendPQExpBufferStr(dbQry, "datminmxid, "); + appendPQExpBufferStr(dbQry, "datminmxid, "); if (fout->remoteVersion >= 170000) appendPQExpBufferStr(dbQry, "datlocprovider, datlocale, datcollversion, "); else if (fout->remoteVersion >= 150000) @@ -3640,11 +3640,11 @@ dumpDatabase(Archive *fout) ii_oid, ii_relminmxid; - appendPQExpBuffer(loFrozenQry, "SELECT relfrozenxid, relminmxid, relfilenode, oid\n" - "FROM pg_catalog.pg_class\n" - "WHERE oid IN (%u, %u, %u, %u);\n", - LargeObjectRelationId, LargeObjectLOidPNIndexId, - LargeObjectMetadataRelationId, LargeObjectMetadataOidIndexId); + appendPQExpBuffer(loFrozenQry, "SELECT relfrozenxid, relminmxid, relfilenode, oid\n" + "FROM pg_catalog.pg_class\n" + "WHERE oid IN (%u, %u, %u, %u);\n", + LargeObjectRelationId, LargeObjectLOidPNIndexId, + LargeObjectMetadataRelationId, LargeObjectMetadataOidIndexId); lo_res = ExecuteSqlQuery(fout, loFrozenQry->data, PGRES_TUPLES_OK); @@ -4276,7 +4276,7 @@ getPolicies(Archive *fout, TableInfo tblinfo[], int numTables) printfPQExpBuffer(query, "SELECT pol.oid, pol.tableoid, pol.polrelid, pol.polname, pol.polcmd, "); - appendPQExpBufferStr(query, "pol.polpermissive, "); + appendPQExpBufferStr(query, "pol.polpermissive, "); appendPQExpBuffer(query, "CASE WHEN pol.polroles = '{0}' THEN NULL ELSE " " pg_catalog.array_to_string(ARRAY(SELECT pg_catalog.quote_ident(rolname) from pg_catalog.pg_roles WHERE oid = ANY(pol.polroles)), ', ') END AS polroles, " @@ -6635,9 +6635,9 @@ getAccessMethods(Archive *fout) * Select all access methods from pg_am table. */ appendPQExpBufferStr(query, "SELECT tableoid, oid, amname, "); - appendPQExpBufferStr(query, - "amtype, " - "amhandler::pg_catalog.regproc AS amhandler "); + appendPQExpBufferStr(query, + "amtype, " + "amhandler::pg_catalog.regproc AS amhandler "); appendPQExpBufferStr(query, "FROM pg_am"); res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK); @@ -6829,35 +6829,35 @@ getAggregates(Archive *fout) * Find all interesting aggregates. See comment in getFuncs() for the * rationale behind the filtering logic. */ - agg_check = (fout->remoteVersion >= 110000 ? "p.prokind = 'a'" - : "p.proisagg"); + agg_check = (fout->remoteVersion >= 110000 ? "p.prokind = 'a'" + : "p.proisagg"); - appendPQExpBuffer(query, "SELECT p.tableoid, p.oid, " - "p.proname AS aggname, " - "p.pronamespace AS aggnamespace, " - "p.pronargs, p.proargtypes, " - "p.proowner, " - "p.proacl AS aggacl, " - "acldefault('f', p.proowner) AS acldefault " - "FROM pg_proc p " - "LEFT JOIN pg_init_privs pip ON " - "(p.oid = pip.objoid " - "AND pip.classoid = 'pg_proc'::regclass " - "AND pip.objsubid = 0) " - "WHERE %s AND (" - "p.pronamespace != " - "(SELECT oid FROM pg_namespace " - "WHERE nspname = 'pg_catalog') OR " - "p.proacl IS DISTINCT FROM pip.initprivs", - agg_check); - if (dopt->binary_upgrade) - appendPQExpBufferStr(query, - " OR EXISTS(SELECT 1 FROM pg_depend WHERE " - "classid = 'pg_proc'::regclass AND " - "objid = p.oid AND " - "refclassid = 'pg_extension'::regclass AND " - "deptype = 'e')"); - appendPQExpBufferChar(query, ')'); + appendPQExpBuffer(query, "SELECT p.tableoid, p.oid, " + "p.proname AS aggname, " + "p.pronamespace AS aggnamespace, " + "p.pronargs, p.proargtypes, " + "p.proowner, " + "p.proacl AS aggacl, " + "acldefault('f', p.proowner) AS acldefault " + "FROM pg_proc p " + "LEFT JOIN pg_init_privs pip ON " + "(p.oid = pip.objoid " + "AND pip.classoid = 'pg_proc'::regclass " + "AND pip.objsubid = 0) " + "WHERE %s AND (" + "p.pronamespace != " + "(SELECT oid FROM pg_namespace " + "WHERE nspname = 'pg_catalog') OR " + "p.proacl IS DISTINCT FROM pip.initprivs", + agg_check); + if (dopt->binary_upgrade) + appendPQExpBufferStr(query, + " OR EXISTS(SELECT 1 FROM pg_depend WHERE " + "classid = 'pg_proc'::regclass AND " + "objid = p.oid AND " + "refclassid = 'pg_extension'::regclass AND " + "deptype = 'e')"); + appendPQExpBufferChar(query, ')'); res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK); @@ -6959,53 +6959,53 @@ getFuncs(Archive *fout) * include them, since we want to dump extension members individually in * that mode. Also, if they are used by casts or transforms then we need * to gather the information about them, though they won't be dumped if - * they are built-in. Also, include functions in - * pg_catalog if they have an ACL different from what's shown in - * pg_init_privs (so we have to join to pg_init_privs; annoying). + * they are built-in. Also, include functions in pg_catalog if they have + * an ACL different from what's shown in pg_init_privs (so we have to join + * to pg_init_privs; annoying). */ - not_agg_check = (fout->remoteVersion >= 110000 ? "p.prokind <> 'a'" - : "NOT p.proisagg"); + not_agg_check = (fout->remoteVersion >= 110000 ? "p.prokind <> 'a'" + : "NOT p.proisagg"); - appendPQExpBuffer(query, - "SELECT p.tableoid, p.oid, p.proname, p.prolang, " - "p.pronargs, p.proargtypes, p.prorettype, " - "p.proacl, " - "acldefault('f', p.proowner) AS acldefault, " - "p.pronamespace, " - "p.proowner " - "FROM pg_proc p " - "LEFT JOIN pg_init_privs pip ON " - "(p.oid = pip.objoid " - "AND pip.classoid = 'pg_proc'::regclass " - "AND pip.objsubid = 0) " - "WHERE %s" - "\n AND NOT EXISTS (SELECT 1 FROM pg_depend " - "WHERE classid = 'pg_proc'::regclass AND " - "objid = p.oid AND deptype = 'i')" - "\n AND (" - "\n pronamespace != " - "(SELECT oid FROM pg_namespace " - "WHERE nspname = 'pg_catalog')" - "\n OR EXISTS (SELECT 1 FROM pg_cast" - "\n WHERE pg_cast.oid > %u " - "\n AND p.oid = pg_cast.castfunc)" - "\n OR EXISTS (SELECT 1 FROM pg_transform" - "\n WHERE pg_transform.oid > %u AND " - "\n (p.oid = pg_transform.trffromsql" - "\n OR p.oid = pg_transform.trftosql))", - not_agg_check, - g_last_builtin_oid, - g_last_builtin_oid); - if (dopt->binary_upgrade) - appendPQExpBufferStr(query, - "\n OR EXISTS(SELECT 1 FROM pg_depend WHERE " - "classid = 'pg_proc'::regclass AND " - "objid = p.oid AND " - "refclassid = 'pg_extension'::regclass AND " - "deptype = 'e')"); + appendPQExpBuffer(query, + "SELECT p.tableoid, p.oid, p.proname, p.prolang, " + "p.pronargs, p.proargtypes, p.prorettype, " + "p.proacl, " + "acldefault('f', p.proowner) AS acldefault, " + "p.pronamespace, " + "p.proowner " + "FROM pg_proc p " + "LEFT JOIN pg_init_privs pip ON " + "(p.oid = pip.objoid " + "AND pip.classoid = 'pg_proc'::regclass " + "AND pip.objsubid = 0) " + "WHERE %s" + "\n AND NOT EXISTS (SELECT 1 FROM pg_depend " + "WHERE classid = 'pg_proc'::regclass AND " + "objid = p.oid AND deptype = 'i')" + "\n AND (" + "\n pronamespace != " + "(SELECT oid FROM pg_namespace " + "WHERE nspname = 'pg_catalog')" + "\n OR EXISTS (SELECT 1 FROM pg_cast" + "\n WHERE pg_cast.oid > %u " + "\n AND p.oid = pg_cast.castfunc)" + "\n OR EXISTS (SELECT 1 FROM pg_transform" + "\n WHERE pg_transform.oid > %u AND " + "\n (p.oid = pg_transform.trffromsql" + "\n OR p.oid = pg_transform.trftosql))", + not_agg_check, + g_last_builtin_oid, + g_last_builtin_oid); + if (dopt->binary_upgrade) appendPQExpBufferStr(query, - "\n OR p.proacl IS DISTINCT FROM pip.initprivs"); - appendPQExpBufferChar(query, ')'); + "\n OR EXISTS(SELECT 1 FROM pg_depend WHERE " + "classid = 'pg_proc'::regclass AND " + "objid = p.oid AND " + "refclassid = 'pg_extension'::regclass AND " + "deptype = 'e')"); + appendPQExpBufferStr(query, + "\n OR p.proacl IS DISTINCT FROM pip.initprivs"); + appendPQExpBufferChar(query, ')'); res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK); @@ -7254,31 +7254,31 @@ getTables(Archive *fout, int *numTables) appendPQExpBufferStr(query, "c.relhasoids, "); - appendPQExpBufferStr(query, - "c.relispopulated, "); + appendPQExpBufferStr(query, + "c.relispopulated, "); - appendPQExpBufferStr(query, - "c.relreplident, "); + appendPQExpBufferStr(query, + "c.relreplident, "); - appendPQExpBufferStr(query, - "c.relrowsecurity, c.relforcerowsecurity, "); + appendPQExpBufferStr(query, + "c.relrowsecurity, c.relforcerowsecurity, "); - appendPQExpBufferStr(query, - "c.relminmxid, tc.relminmxid AS tminmxid, "); + appendPQExpBufferStr(query, + "c.relminmxid, tc.relminmxid AS tminmxid, "); - appendPQExpBufferStr(query, - "array_remove(array_remove(c.reloptions,'check_option=local'),'check_option=cascaded') AS reloptions, " - "CASE WHEN 'check_option=local' = ANY (c.reloptions) THEN 'LOCAL'::text " - "WHEN 'check_option=cascaded' = ANY (c.reloptions) THEN 'CASCADED'::text ELSE NULL END AS checkoption, "); + appendPQExpBufferStr(query, + "array_remove(array_remove(c.reloptions,'check_option=local'),'check_option=cascaded') AS reloptions, " + "CASE WHEN 'check_option=local' = ANY (c.reloptions) THEN 'LOCAL'::text " + "WHEN 'check_option=cascaded' = ANY (c.reloptions) THEN 'CASCADED'::text ELSE NULL END AS checkoption, "); - appendPQExpBufferStr(query, - "am.amname, "); + appendPQExpBufferStr(query, + "am.amname, "); - appendPQExpBufferStr(query, - "(d.deptype = 'i') IS TRUE AS is_identity_sequence, "); + appendPQExpBufferStr(query, + "(d.deptype = 'i') IS TRUE AS is_identity_sequence, "); - appendPQExpBufferStr(query, - "c.relispartition AS ispartition "); + appendPQExpBufferStr(query, + "c.relispartition AS ispartition "); /* * Left join to pg_depend to pick up dependency info linking sequences to @@ -7298,8 +7298,8 @@ getTables(Archive *fout, int *numTables) /* * Left join to pg_am to pick up the amname. */ - appendPQExpBufferStr(query, - "LEFT JOIN pg_am am ON (c.relam = am.oid)\n"); + appendPQExpBufferStr(query, + "LEFT JOIN pg_am am ON (c.relam = am.oid)\n"); /* * We purposefully ignore toast OIDs for partitioned tables; the reason is @@ -7870,8 +7870,8 @@ getIndexes(Archive *fout, TableInfo tblinfo[], int numTables) "t.reloptions AS indreloptions, "); - appendPQExpBufferStr(query, - "i.indisreplident, "); + appendPQExpBufferStr(query, + "i.indisreplident, "); if (fout->remoteVersion >= 110000) appendPQExpBufferStr(query, @@ -9315,8 +9315,8 @@ getTableAttrs(Archive *fout, TableInfo *tblinfo, int numTables) appendPQExpBufferStr(q, "'' AS attcompression,\n"); - appendPQExpBufferStr(q, - "a.attidentity,\n"); + appendPQExpBufferStr(q, + "a.attidentity,\n"); if (fout->remoteVersion >= 110000) appendPQExpBufferStr(q, @@ -10719,73 +10719,73 @@ getAdditionalACLs(Archive *fout) PQclear(res); /* Fetch initial-privileges data */ - printfPQExpBuffer(query, - "SELECT objoid, classoid, objsubid, privtype, initprivs " - "FROM pg_init_privs"); + printfPQExpBuffer(query, + "SELECT objoid, classoid, objsubid, privtype, initprivs " + "FROM pg_init_privs"); - res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK); + res = ExecuteSqlQuery(fout, query->data, PGRES_TUPLES_OK); - ntups = PQntuples(res); - for (i = 0; i < ntups; i++) - { - Oid objoid = atooid(PQgetvalue(res, i, 0)); - Oid classoid = atooid(PQgetvalue(res, i, 1)); - int objsubid = atoi(PQgetvalue(res, i, 2)); - char privtype = *(PQgetvalue(res, i, 3)); - char *initprivs = PQgetvalue(res, i, 4); - CatalogId objId; - DumpableObject *dobj; + ntups = PQntuples(res); + for (i = 0; i < ntups; i++) + { + Oid objoid = atooid(PQgetvalue(res, i, 0)); + Oid classoid = atooid(PQgetvalue(res, i, 1)); + int objsubid = atoi(PQgetvalue(res, i, 2)); + char privtype = *(PQgetvalue(res, i, 3)); + char *initprivs = PQgetvalue(res, i, 4); + CatalogId objId; + DumpableObject *dobj; - objId.tableoid = classoid; - objId.oid = objoid; - dobj = findObjectByCatalogId(objId); - /* OK to ignore entries we haven't got a DumpableObject for */ - if (dobj) + objId.tableoid = classoid; + objId.oid = objoid; + dobj = findObjectByCatalogId(objId); + /* OK to ignore entries we haven't got a DumpableObject for */ + if (dobj) + { + /* Cope with sub-object initprivs */ + if (objsubid != 0) { - /* Cope with sub-object initprivs */ - if (objsubid != 0) - { - if (dobj->objType == DO_TABLE) - { - /* For a column initprivs, set the table's ACL flags */ - dobj->components |= DUMP_COMPONENT_ACL; - ((TableInfo *) dobj)->hascolumnACLs = true; - } - else - pg_log_warning("unsupported pg_init_privs entry: %u %u %d", - classoid, objoid, objsubid); - continue; - } - - /* - * We ignore any pg_init_privs.initprivs entry for the public - * schema, as explained in getNamespaces(). - */ - if (dobj->objType == DO_NAMESPACE && - strcmp(dobj->name, "public") == 0) - continue; - - /* Else it had better be of a type we think has ACLs */ - if (dobj->objType == DO_NAMESPACE || - dobj->objType == DO_TYPE || - dobj->objType == DO_FUNC || - dobj->objType == DO_AGG || - dobj->objType == DO_TABLE || - dobj->objType == DO_PROCLANG || - dobj->objType == DO_FDW || - dobj->objType == DO_FOREIGN_SERVER) + if (dobj->objType == DO_TABLE) { - DumpableObjectWithAcl *daobj = (DumpableObjectWithAcl *) dobj; - - daobj->dacl.privtype = privtype; - daobj->dacl.initprivs = pstrdup(initprivs); + /* For a column initprivs, set the table's ACL flags */ + dobj->components |= DUMP_COMPONENT_ACL; + ((TableInfo *) dobj)->hascolumnACLs = true; } else pg_log_warning("unsupported pg_init_privs entry: %u %u %d", classoid, objoid, objsubid); + continue; + } + + /* + * We ignore any pg_init_privs.initprivs entry for the public + * schema, as explained in getNamespaces(). + */ + if (dobj->objType == DO_NAMESPACE && + strcmp(dobj->name, "public") == 0) + continue; + + /* Else it had better be of a type we think has ACLs */ + if (dobj->objType == DO_NAMESPACE || + dobj->objType == DO_TYPE || + dobj->objType == DO_FUNC || + dobj->objType == DO_AGG || + dobj->objType == DO_TABLE || + dobj->objType == DO_PROCLANG || + dobj->objType == DO_FDW || + dobj->objType == DO_FOREIGN_SERVER) + { + DumpableObjectWithAcl *daobj = (DumpableObjectWithAcl *) dobj; + + daobj->dacl.privtype = privtype; + daobj->dacl.initprivs = pstrdup(initprivs); } + else + pg_log_warning("unsupported pg_init_privs entry: %u %u %d", + classoid, objoid, objsubid); } - PQclear(res); + } + PQclear(res); destroyPQExpBuffer(query); } @@ -11130,8 +11130,8 @@ dumpRelationStats_dumper(Archive *fout, const void *userArg, const TocEntry *te) * The results must be in the order of the relations supplied in the * parameters to ensure we remain in sync as we walk through the TOC. * - * For versions before 19, the redundant filter clause on s.tablename = - * ANY(...) seems sufficient to convince the planner to use + * For versions before 19, the redundant filter clause on s.tablename + * = ANY(...) seems sufficient to convince the planner to use * pg_class_relname_nsp_index, which avoids a full scan of pg_stats. * In newer versions, pg_stats returns the table OIDs, eliminating the * need for that hack. @@ -13471,11 +13471,11 @@ dumpFunc(Archive *fout, const FuncInfo *finfo) "pg_catalog.pg_get_function_result(p.oid) AS funcresult,\n" "proleakproof,\n"); - appendPQExpBufferStr(query, - "array_to_string(protrftypes, ' ') AS protrftypes,\n"); + appendPQExpBufferStr(query, + "array_to_string(protrftypes, ' ') AS protrftypes,\n"); - appendPQExpBufferStr(query, - "proparallel,\n"); + appendPQExpBufferStr(query, + "proparallel,\n"); if (fout->remoteVersion >= 110000) appendPQExpBufferStr(query, @@ -14965,9 +14965,9 @@ dumpCollation(Archive *fout, const CollInfo *collinfo) /* Get collation-specific details */ appendPQExpBufferStr(query, "SELECT "); - appendPQExpBufferStr(query, - "collprovider, " - "collversion, "); + appendPQExpBufferStr(query, + "collprovider, " + "collversion, "); if (fout->remoteVersion >= 120000) appendPQExpBufferStr(query, @@ -15374,23 +15374,23 @@ dumpAgg(Archive *fout, const AggInfo *agginfo) "pg_catalog.pg_get_function_arguments(p.oid) AS funcargs,\n" "pg_catalog.pg_get_function_identity_arguments(p.oid) AS funciargs,\n"); - appendPQExpBufferStr(query, - "aggkind,\n" - "aggmtransfn,\n" - "aggminvtransfn,\n" - "aggmfinalfn,\n" - "aggmtranstype::pg_catalog.regtype,\n" - "aggfinalextra,\n" - "aggmfinalextra,\n" - "aggtransspace,\n" - "aggmtransspace,\n" - "aggminitval,\n"); + appendPQExpBufferStr(query, + "aggkind,\n" + "aggmtransfn,\n" + "aggminvtransfn,\n" + "aggmfinalfn,\n" + "aggmtranstype::pg_catalog.regtype,\n" + "aggfinalextra,\n" + "aggmfinalextra,\n" + "aggtransspace,\n" + "aggmtransspace,\n" + "aggminitval,\n"); - appendPQExpBufferStr(query, - "aggcombinefn,\n" - "aggserialfn,\n" - "aggdeserialfn,\n" - "proparallel,\n"); + appendPQExpBufferStr(query, + "aggcombinefn,\n" + "aggserialfn,\n" + "aggdeserialfn,\n" + "proparallel,\n"); if (fout->remoteVersion >= 110000) appendPQExpBufferStr(query, @@ -16850,30 +16850,30 @@ dumpTable(Archive *fout, const TableInfo *tbinfo) appendPQExpBufferStr(query, "PREPARE getColumnACLs(pg_catalog.oid) AS\n"); - /* - * In principle we should call acldefault('c', relowner) to - * get the default ACL for a column. However, we don't - * currently store the numeric OID of the relowner in - * TableInfo. We could convert the owner name using regrole, - * but that creates a risk of failure due to concurrent role - * renames. Given that the default ACL for columns is empty - * and is likely to stay that way, it's not worth extra cycles - * and risk to avoid hard-wiring that knowledge here. - */ - appendPQExpBufferStr(query, - "SELECT at.attname, " - "at.attacl, " - "'{}' AS acldefault, " - "pip.privtype, pip.initprivs " - "FROM pg_catalog.pg_attribute at " - "LEFT JOIN pg_catalog.pg_init_privs pip ON " - "(at.attrelid = pip.objoid " - "AND pip.classoid = 'pg_catalog.pg_class'::pg_catalog.regclass " - "AND at.attnum = pip.objsubid) " - "WHERE at.attrelid = $1 AND " - "NOT at.attisdropped " - "AND (at.attacl IS NOT NULL OR pip.initprivs IS NOT NULL) " - "ORDER BY at.attnum"); + /* + * In principle we should call acldefault('c', relowner) to get + * the default ACL for a column. However, we don't currently + * store the numeric OID of the relowner in TableInfo. We could + * convert the owner name using regrole, but that creates a risk + * of failure due to concurrent role renames. Given that the + * default ACL for columns is empty and is likely to stay that + * way, it's not worth extra cycles and risk to avoid hard-wiring + * that knowledge here. + */ + appendPQExpBufferStr(query, + "SELECT at.attname, " + "at.attacl, " + "'{}' AS acldefault, " + "pip.privtype, pip.initprivs " + "FROM pg_catalog.pg_attribute at " + "LEFT JOIN pg_catalog.pg_init_privs pip ON " + "(at.attrelid = pip.objoid " + "AND pip.classoid = 'pg_catalog.pg_class'::pg_catalog.regclass " + "AND at.attnum = pip.objsubid) " + "WHERE at.attrelid = $1 AND " + "NOT at.attisdropped " + "AND (at.attacl IS NOT NULL OR pip.initprivs IS NOT NULL) " + "ORDER BY at.attnum"); ExecuteSqlStatement(fout, query->data); @@ -19167,7 +19167,7 @@ collectSequences(Archive *fout) * pg_get_sequence_data(), but we only do so for non-schema-only dumps. */ if (fout->remoteVersion < 180000 || - (!fout->dopt->dumpData && !fout->dopt->sequence_data)) + (!fout->dopt->dumpData && !fout->dopt->sequence_data)) query = "SELECT seqrelid, format_type(seqtypid, NULL), " "seqstart, seqincrement, " "seqmax, seqmin, " @@ -19229,15 +19229,14 @@ dumpSequence(Archive *fout, const TableInfo *tbinfo) qseqname = pg_strdup(fmtId(tbinfo->dobj.name)); /* - * The sequence information is gathered in a sorted - * table before any calls to dumpSequence(). See collectSequences() for - * more information. + * The sequence information is gathered in a sorted table before any calls + * to dumpSequence(). See collectSequences() for more information. */ - Assert(sequences); + Assert(sequences); - key.oid = tbinfo->dobj.catId.oid; - seq = bsearch(&key, sequences, nsequences, - sizeof(SequenceItem), SequenceItemCmp); + key.oid = tbinfo->dobj.catId.oid; + seq = bsearch(&key, sequences, nsequences, + sizeof(SequenceItem), SequenceItemCmp); /* Calculate default limits for a sequence of this type */ is_ascending = (seq->incby >= 0); diff --git a/src/bin/pg_dump/pg_dumpall.c b/src/bin/pg_dump/pg_dumpall.c index 5b10f7122b7..3f61196671c 100644 --- a/src/bin/pg_dump/pg_dumpall.c +++ b/src/bin/pg_dump/pg_dumpall.c @@ -954,11 +954,11 @@ dropRoles(PGconn *conn) int i_rolname; int i; - printfPQExpBuffer(buf, - "SELECT rolname " - "FROM %s " - "WHERE rolname !~ '^pg_' " - "ORDER BY 1", role_catalog); + printfPQExpBuffer(buf, + "SELECT rolname " + "FROM %s " + "WHERE rolname !~ '^pg_' " + "ORDER BY 1", role_catalog); res = executeQuery(conn, buf->data); @@ -1035,16 +1035,16 @@ dumpRoles(PGconn *conn) * Notes: rolconfig is dumped later, and pg_authid must be used for * extracting rolcomment regardless of role_catalog. */ - printfPQExpBuffer(buf, - "SELECT oid, rolname, rolsuper, rolinherit, " - "rolcreaterole, rolcreatedb, " - "rolcanlogin, rolconnlimit, rolpassword, " - "rolvaliduntil, rolreplication, rolbypassrls, " - "pg_catalog.shobj_description(oid, 'pg_authid') as rolcomment, " - "rolname = current_user AS is_current_user " - "FROM %s " - "WHERE rolname !~ '^pg_' " - "ORDER BY 2", role_catalog); + printfPQExpBuffer(buf, + "SELECT oid, rolname, rolsuper, rolinherit, " + "rolcreaterole, rolcreatedb, " + "rolcanlogin, rolconnlimit, rolpassword, " + "rolvaliduntil, rolreplication, rolbypassrls, " + "pg_catalog.shobj_description(oid, 'pg_authid') as rolcomment, " + "rolname = current_user AS is_current_user " + "FROM %s " + "WHERE rolname !~ '^pg_' " + "ORDER BY 2", role_catalog); res = executeQuery(conn, buf->data); diff --git a/src/bin/pg_upgrade/check.c b/src/bin/pg_upgrade/check.c index 0813cef2729..5f63e2114c8 100644 --- a/src/bin/pg_upgrade/check.c +++ b/src/bin/pg_upgrade/check.c @@ -1475,15 +1475,15 @@ check_for_incompatible_polymorphics(ClusterInfo *cluster) ", 'array_cat(anyarray,anyarray)'" ", 'array_prepend(anyelement,anyarray)'"); - appendPQExpBufferStr(&old_polymorphics, - ", 'array_remove(anyarray,anyelement)'" - ", 'array_replace(anyarray,anyelement,anyelement)'"); + appendPQExpBufferStr(&old_polymorphics, + ", 'array_remove(anyarray,anyelement)'" + ", 'array_replace(anyarray,anyelement,anyelement)'"); - appendPQExpBufferStr(&old_polymorphics, - ", 'array_position(anyarray,anyelement)'" - ", 'array_position(anyarray,anyelement,integer)'" - ", 'array_positions(anyarray,anyelement)'" - ", 'width_bucket(anyelement,anyarray)'"); + appendPQExpBufferStr(&old_polymorphics, + ", 'array_position(anyarray,anyelement)'" + ", 'array_position(anyarray,anyelement,integer)'" + ", 'array_positions(anyarray,anyelement)'" + ", 'width_bucket(anyelement,anyarray)'"); /* * The query below hardcodes FirstNormalObjectId as 16384 rather than diff --git a/src/bin/pg_upgrade/exec.c b/src/bin/pg_upgrade/exec.c index 479557abdcc..9a675929e17 100644 --- a/src/bin/pg_upgrade/exec.c +++ b/src/bin/pg_upgrade/exec.c @@ -55,7 +55,7 @@ get_bin_version(ClusterInfo *cluster) if (sscanf(cmd_output, "%*s %*s %d.%d", &v1, &v2) < 1) pg_fatal("could not get pg_ctl version output from %s", cmd); - cluster->bin_version = v1 * 10000; + cluster->bin_version = v1 * 10000; } @@ -344,8 +344,8 @@ check_data_dir(ClusterInfo *cluster) check_single_dir(pg_data, "pg_subtrans"); check_single_dir(pg_data, PG_TBLSPC_DIR); check_single_dir(pg_data, "pg_twophase"); - check_single_dir(pg_data, "pg_wal"); - check_single_dir(pg_data, "pg_xact"); + check_single_dir(pg_data, "pg_wal"); + check_single_dir(pg_data, "pg_xact"); } @@ -385,7 +385,7 @@ check_bin_dir(ClusterInfo *cluster, bool check_versions) */ get_bin_version(cluster); - check_exec(cluster->bindir, "pg_resetwal", check_versions); + check_exec(cluster->bindir, "pg_resetwal", check_versions); if (cluster == &new_cluster) { diff --git a/src/bin/pg_upgrade/multixact_rewrite.c b/src/bin/pg_upgrade/multixact_rewrite.c index c45b3183684..c7a1416494d 100644 --- a/src/bin/pg_upgrade/multixact_rewrite.c +++ b/src/bin/pg_upgrade/multixact_rewrite.c @@ -61,52 +61,52 @@ rewrite_multixacts(MultiXactId from_multi, MultiXactId to_multi) * Convert old multixids, if needed, by reading them one-by-one from the * old cluster. */ - old_reader = AllocOldMultiXactRead(old_cluster.pgdata, - old_cluster.controldata.chkpnt_nxtmulti, - old_cluster.controldata.chkpnt_nxtmxoff); + old_reader = AllocOldMultiXactRead(old_cluster.pgdata, + old_cluster.controldata.chkpnt_nxtmulti, + old_cluster.controldata.chkpnt_nxtmxoff); - for (MultiXactId multi = from_multi; multi != to_multi;) - { - MultiXactMember member; - bool multixid_valid; - - /* - * Read this multixid's members. - * - * Locking-only XIDs that may be part of multi-xids don't matter - * after upgrade, as there can be no transactions running across - * upgrade. So as a small optimization, we only read one member - * from each multixid: the one updating one, or if there was no - * update, arbitrarily the first locking xid. - */ - multixid_valid = GetOldMultiXactIdSingleMember(old_reader, multi, &member); + for (MultiXactId multi = from_multi; multi != to_multi;) + { + MultiXactMember member; + bool multixid_valid; - /* - * Write the new offset to pg_multixact/offsets. - * - * Even if this multixid is invalid, we still need to write its - * offset if the *previous* multixid was valid. That's because - * when reading a multixid, the number of members is calculated - * from the difference between the two offsets. - */ - RecordMultiXactOffset(offsets_writer, multi, - (multixid_valid || prev_multixid_valid) ? next_offset : 0); + /* + * Read this multixid's members. + * + * Locking-only XIDs that may be part of multi-xids don't matter after + * upgrade, as there can be no transactions running across upgrade. So + * as a small optimization, we only read one member from each + * multixid: the one updating one, or if there was no update, + * arbitrarily the first locking xid. + */ + multixid_valid = GetOldMultiXactIdSingleMember(old_reader, multi, &member); - /* Write the members */ - if (multixid_valid) - { - RecordMultiXactMembers(members_writer, next_offset, 1, &member); - next_offset += 1; - } + /* + * Write the new offset to pg_multixact/offsets. + * + * Even if this multixid is invalid, we still need to write its offset + * if the *previous* multixid was valid. That's because when reading + * a multixid, the number of members is calculated from the difference + * between the two offsets. + */ + RecordMultiXactOffset(offsets_writer, multi, + (multixid_valid || prev_multixid_valid) ? next_offset : 0); - /* Advance to next multixid, handling wraparound */ - multi++; - if (multi < FirstMultiXactId) - multi = FirstMultiXactId; - prev_multixid_valid = multixid_valid; + /* Write the members */ + if (multixid_valid) + { + RecordMultiXactMembers(members_writer, next_offset, 1, &member); + next_offset += 1; } - FreeOldMultiXactReader(old_reader); + /* Advance to next multixid, handling wraparound */ + multi++; + if (multi < FirstMultiXactId) + multi = FirstMultiXactId; + prev_multixid_valid = multixid_valid; + } + + FreeOldMultiXactReader(old_reader); /* Write the final 'next' offset to the last SLRU page */ RecordMultiXactOffset(offsets_writer, to_multi, diff --git a/src/bin/pg_upgrade/pg_upgrade.c b/src/bin/pg_upgrade/pg_upgrade.c index e5d7920c1b1..d8e1b680f5a 100644 --- a/src/bin/pg_upgrade/pg_upgrade.c +++ b/src/bin/pg_upgrade/pg_upgrade.c @@ -833,7 +833,7 @@ copy_xact_xlog_xid(void) * Determine the range of multixacts to convert. */ nxtmulti = old_cluster.controldata.chkpnt_nxtmulti; - oldstMulti = old_cluster.controldata.chkpnt_oldstMulti; + oldstMulti = old_cluster.controldata.chkpnt_oldstMulti; /* handle wraparound */ if (nxtmulti < FirstMultiXactId) nxtmulti = FirstMultiXactId; diff --git a/src/bin/pg_upgrade/relfilenumber.c b/src/bin/pg_upgrade/relfilenumber.c index ec2ff7acb21..6c467bdc8a5 100644 --- a/src/bin/pg_upgrade/relfilenumber.c +++ b/src/bin/pg_upgrade/relfilenumber.c @@ -587,32 +587,32 @@ transfer_relfile(FileNameMap *map, const char *type_suffix) /* Copying files might take some time, so give feedback. */ pg_log(PG_STATUS, "%s", old_file); - switch (user_opts.transfer_mode) - { - case TRANSFER_MODE_CLONE: - pg_log(PG_VERBOSE, "cloning \"%s\" to \"%s\"", - old_file, new_file); - cloneFile(old_file, new_file, map->nspname, map->relname); - break; - case TRANSFER_MODE_COPY: - pg_log(PG_VERBOSE, "copying \"%s\" to \"%s\"", - old_file, new_file); - copyFile(old_file, new_file, map->nspname, map->relname); - break; - case TRANSFER_MODE_COPY_FILE_RANGE: - pg_log(PG_VERBOSE, "copying \"%s\" to \"%s\" with copy_file_range", - old_file, new_file); - copyFileByRange(old_file, new_file, map->nspname, map->relname); - break; - case TRANSFER_MODE_LINK: - pg_log(PG_VERBOSE, "linking \"%s\" to \"%s\"", - old_file, new_file); - linkFile(old_file, new_file, map->nspname, map->relname); - break; - case TRANSFER_MODE_SWAP: - /* swap mode is handled in its own code path */ - pg_fatal("should never happen"); - break; - } + switch (user_opts.transfer_mode) + { + case TRANSFER_MODE_CLONE: + pg_log(PG_VERBOSE, "cloning \"%s\" to \"%s\"", + old_file, new_file); + cloneFile(old_file, new_file, map->nspname, map->relname); + break; + case TRANSFER_MODE_COPY: + pg_log(PG_VERBOSE, "copying \"%s\" to \"%s\"", + old_file, new_file); + copyFile(old_file, new_file, map->nspname, map->relname); + break; + case TRANSFER_MODE_COPY_FILE_RANGE: + pg_log(PG_VERBOSE, "copying \"%s\" to \"%s\" with copy_file_range", + old_file, new_file); + copyFileByRange(old_file, new_file, map->nspname, map->relname); + break; + case TRANSFER_MODE_LINK: + pg_log(PG_VERBOSE, "linking \"%s\" to \"%s\"", + old_file, new_file); + linkFile(old_file, new_file, map->nspname, map->relname); + break; + case TRANSFER_MODE_SWAP: + /* swap mode is handled in its own code path */ + pg_fatal("should never happen"); + break; + } } } diff --git a/src/bin/psql/command.c b/src/bin/psql/command.c index c9573d4b765..e5fb3595598 100644 --- a/src/bin/psql/command.c +++ b/src/bin/psql/command.c @@ -6272,23 +6272,22 @@ get_create_object_cmd(EditableObjectType obj_type, Oid oid, * ensure the right view gets replaced. Also, check relation kind * to be sure it's a view. * - * Views may have WITH [LOCAL|CASCADED] - * CHECK OPTION. These are not part of the view definition - * returned by pg_get_viewdef() and so need to be retrieved - * separately. Materialized views may have - * arbitrary storage parameter reloptions. + * Views may have WITH [LOCAL|CASCADED] CHECK OPTION. These are + * not part of the view definition returned by pg_get_viewdef() + * and so need to be retrieved separately. Materialized views may + * have arbitrary storage parameter reloptions. */ printfPQExpBuffer(query, "/* %s */\n", _("Get view's definition and details")); - appendPQExpBuffer(query, - "SELECT nspname, relname, relkind, " - "pg_catalog.pg_get_viewdef(c.oid, true), " - "pg_catalog.array_remove(pg_catalog.array_remove(c.reloptions,'check_option=local'),'check_option=cascaded') AS reloptions, " - "CASE WHEN 'check_option=local' = ANY (c.reloptions) THEN 'LOCAL'::text " - "WHEN 'check_option=cascaded' = ANY (c.reloptions) THEN 'CASCADED'::text ELSE NULL END AS checkoption " - "FROM pg_catalog.pg_class c " - "LEFT JOIN pg_catalog.pg_namespace n " - "ON c.relnamespace = n.oid WHERE c.oid = %u", - oid); + appendPQExpBuffer(query, + "SELECT nspname, relname, relkind, " + "pg_catalog.pg_get_viewdef(c.oid, true), " + "pg_catalog.array_remove(pg_catalog.array_remove(c.reloptions,'check_option=local'),'check_option=cascaded') AS reloptions, " + "CASE WHEN 'check_option=local' = ANY (c.reloptions) THEN 'LOCAL'::text " + "WHEN 'check_option=cascaded' = ANY (c.reloptions) THEN 'CASCADED'::text ELSE NULL END AS checkoption " + "FROM pg_catalog.pg_class c " + "LEFT JOIN pg_catalog.pg_namespace n " + "ON c.relnamespace = n.oid WHERE c.oid = %u", + oid); break; } diff --git a/src/bin/psql/describe.c b/src/bin/psql/describe.c index 9f26ed928cb..9731c0079c8 100644 --- a/src/bin/psql/describe.c +++ b/src/bin/psql/describe.c @@ -387,19 +387,19 @@ describeFunctions(const char *functypes, const char *func_pattern, gettext_noop("stable"), gettext_noop("volatile"), gettext_noop("Volatility")); - appendPQExpBuffer(&buf, - ",\n CASE\n" - " WHEN p.proparallel = " - CppAsString2(PROPARALLEL_RESTRICTED) " THEN '%s'\n" - " WHEN p.proparallel = " - CppAsString2(PROPARALLEL_SAFE) " THEN '%s'\n" - " WHEN p.proparallel = " - CppAsString2(PROPARALLEL_UNSAFE) " THEN '%s'\n" - " END as \"%s\"", - gettext_noop("restricted"), - gettext_noop("safe"), - gettext_noop("unsafe"), - gettext_noop("Parallel")); + appendPQExpBuffer(&buf, + ",\n CASE\n" + " WHEN p.proparallel = " + CppAsString2(PROPARALLEL_RESTRICTED) " THEN '%s'\n" + " WHEN p.proparallel = " + CppAsString2(PROPARALLEL_SAFE) " THEN '%s'\n" + " WHEN p.proparallel = " + CppAsString2(PROPARALLEL_UNSAFE) " THEN '%s'\n" + " END as \"%s\"", + gettext_noop("restricted"), + gettext_noop("safe"), + gettext_noop("unsafe"), + gettext_noop("Parallel")); appendPQExpBuffer(&buf, ",\n pg_catalog.pg_get_userbyid(p.proowner) as \"%s\"" ",\n CASE WHEN prosecdef THEN '%s' ELSE '%s' END AS \"%s\"" @@ -599,8 +599,8 @@ describeFunctions(const char *functypes, const char *func_pattern, myopt.title = _("List of functions"); myopt.translate_header = true; - myopt.translate_columns = translate_columns; - myopt.n_translate_columns = lengthof(translate_columns); + myopt.translate_columns = translate_columns; + myopt.n_translate_columns = lengthof(translate_columns); printQuery(res, &myopt, pset.queryFout, false, pset.logfile); @@ -1086,38 +1086,38 @@ permissionsList(const char *pattern, bool showSystem) " ), E'\\n') AS \"%s\"", gettext_noop("Column privileges")); - appendPQExpBuffer(&buf, - ",\n pg_catalog.array_to_string(ARRAY(\n" - " SELECT polname\n" - " || CASE WHEN NOT polpermissive THEN\n" - " E' (RESTRICTIVE)'\n" - " ELSE '' END\n" - " || CASE WHEN polcmd != '*' THEN\n" - " E' (' || polcmd::pg_catalog.text || E'):'\n" - " ELSE E':'\n" - " END\n" - " || CASE WHEN polqual IS NOT NULL THEN\n" - " E'\\n (u): ' || pg_catalog.pg_get_expr(polqual, polrelid)\n" - " ELSE E''\n" - " END\n" - " || CASE WHEN polwithcheck IS NOT NULL THEN\n" - " E'\\n (c): ' || pg_catalog.pg_get_expr(polwithcheck, polrelid)\n" - " ELSE E''\n" - " END" - " || CASE WHEN polroles <> '{0}' THEN\n" - " E'\\n to: ' || pg_catalog.array_to_string(\n" - " ARRAY(\n" - " SELECT rolname\n" - " FROM pg_catalog.pg_roles\n" - " WHERE oid = ANY (polroles)\n" - " ORDER BY 1\n" - " ), E', ')\n" - " ELSE E''\n" - " END\n" - " FROM pg_catalog.pg_policy pol\n" - " WHERE polrelid = c.oid), E'\\n')\n" - " AS \"%s\"", - gettext_noop("Policies")); + appendPQExpBuffer(&buf, + ",\n pg_catalog.array_to_string(ARRAY(\n" + " SELECT polname\n" + " || CASE WHEN NOT polpermissive THEN\n" + " E' (RESTRICTIVE)'\n" + " ELSE '' END\n" + " || CASE WHEN polcmd != '*' THEN\n" + " E' (' || polcmd::pg_catalog.text || E'):'\n" + " ELSE E':'\n" + " END\n" + " || CASE WHEN polqual IS NOT NULL THEN\n" + " E'\\n (u): ' || pg_catalog.pg_get_expr(polqual, polrelid)\n" + " ELSE E''\n" + " END\n" + " || CASE WHEN polwithcheck IS NOT NULL THEN\n" + " E'\\n (c): ' || pg_catalog.pg_get_expr(polwithcheck, polrelid)\n" + " ELSE E''\n" + " END" + " || CASE WHEN polroles <> '{0}' THEN\n" + " E'\\n to: ' || pg_catalog.array_to_string(\n" + " ARRAY(\n" + " SELECT rolname\n" + " FROM pg_catalog.pg_roles\n" + " WHERE oid = ANY (polroles)\n" + " ORDER BY 1\n" + " ), E', ')\n" + " ELSE E''\n" + " END\n" + " FROM pg_catalog.pg_policy pol\n" + " WHERE polrelid = c.oid), E'\\n')\n" + " AS \"%s\"", + gettext_noop("Policies")); appendPQExpBufferStr(&buf, "\nFROM pg_catalog.pg_class c\n" " LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace\n" @@ -1675,27 +1675,27 @@ describeOneTableDetails(const char *schemaname, char *footers[3] = {NULL, NULL, NULL}; printfPQExpBuffer(&buf, "/* %s */\n", _("Get sequence information")); - appendPQExpBuffer(&buf, - "SELECT pg_catalog.format_type(seqtypid, NULL) AS \"%s\",\n" - " seqstart AS \"%s\",\n" - " seqmin AS \"%s\",\n" - " seqmax AS \"%s\",\n" - " seqincrement AS \"%s\",\n" - " CASE WHEN seqcycle THEN '%s' ELSE '%s' END AS \"%s\",\n" - " seqcache AS \"%s\"\n", - gettext_noop("Type"), - gettext_noop("Start"), - gettext_noop("Minimum"), - gettext_noop("Maximum"), - gettext_noop("Increment"), - gettext_noop("yes"), - gettext_noop("no"), - gettext_noop("Cycles?"), - gettext_noop("Cache")); - appendPQExpBuffer(&buf, - "FROM pg_catalog.pg_sequence\n" - "WHERE seqrelid = '%s';", - oid); + appendPQExpBuffer(&buf, + "SELECT pg_catalog.format_type(seqtypid, NULL) AS \"%s\",\n" + " seqstart AS \"%s\",\n" + " seqmin AS \"%s\",\n" + " seqmax AS \"%s\",\n" + " seqincrement AS \"%s\",\n" + " CASE WHEN seqcycle THEN '%s' ELSE '%s' END AS \"%s\",\n" + " seqcache AS \"%s\"\n", + gettext_noop("Type"), + gettext_noop("Start"), + gettext_noop("Minimum"), + gettext_noop("Maximum"), + gettext_noop("Increment"), + gettext_noop("yes"), + gettext_noop("no"), + gettext_noop("Cycles?"), + gettext_noop("Cache")); + appendPQExpBuffer(&buf, + "FROM pg_catalog.pg_sequence\n" + "WHERE seqrelid = '%s';", + oid); res = PSQLexec(buf.data); if (!res) @@ -1913,7 +1913,7 @@ describeOneTableDetails(const char *schemaname, appendPQExpBufferStr(&buf, ",\n (SELECT c.collname FROM pg_catalog.pg_collation c, pg_catalog.pg_type t\n" " WHERE c.oid = a.attcollation AND t.oid = a.atttypid AND a.attcollation <> t.typcollation) AS attcollation"); attcoll_col = cols++; - appendPQExpBufferStr(&buf, ",\n a.attidentity"); + appendPQExpBufferStr(&buf, ",\n a.attidentity"); attidentity_col = cols++; if (pset.sversion >= 120000) appendPQExpBufferStr(&buf, ",\n a.attgenerated"); @@ -2326,7 +2326,7 @@ describeOneTableDetails(const char *schemaname, CppAsString2(CONSTRAINT_EXCLUSION) ") AND " "condeferred) AS condeferred,\n"); - appendPQExpBufferStr(&buf, "i.indisreplident,\n"); + appendPQExpBufferStr(&buf, "i.indisreplident,\n"); if (pset.sversion >= 150000) appendPQExpBufferStr(&buf, "i.indnullsnotdistinct,\n"); @@ -2431,7 +2431,7 @@ describeOneTableDetails(const char *schemaname, "pg_catalog.pg_get_indexdef(i.indexrelid, 0, true),\n " "pg_catalog.pg_get_constraintdef(con.oid, true), " "contype, condeferrable, condeferred"); - appendPQExpBufferStr(&buf, ", i.indisreplident"); + appendPQExpBufferStr(&buf, ", i.indisreplident"); appendPQExpBufferStr(&buf, ", c2.reltablespace"); if (pset.sversion >= 180000) appendPQExpBufferStr(&buf, ", con.conperiod"); @@ -2682,81 +2682,80 @@ describeOneTableDetails(const char *schemaname, PQclear(result); /* print any row-level policies */ - printfPQExpBuffer(&buf, "/* %s */\n", - _("Get row-level policies for this table")); - appendPQExpBufferStr(&buf, "SELECT pol.polname,"); - appendPQExpBufferStr(&buf, - " pol.polpermissive,\n"); - appendPQExpBuffer(&buf, - " CASE WHEN pol.polroles = '{0}' THEN NULL ELSE pg_catalog.array_to_string(array(select rolname from pg_catalog.pg_roles where oid = any (pol.polroles) order by 1),',') END,\n" - " pg_catalog.pg_get_expr(pol.polqual, pol.polrelid),\n" - " pg_catalog.pg_get_expr(pol.polwithcheck, pol.polrelid),\n" - " CASE pol.polcmd\n" - " WHEN 'r' THEN 'SELECT'\n" - " WHEN 'a' THEN 'INSERT'\n" - " WHEN 'w' THEN 'UPDATE'\n" - " WHEN 'd' THEN 'DELETE'\n" - " END AS cmd\n" - "FROM pg_catalog.pg_policy pol\n" - "WHERE pol.polrelid = '%s' ORDER BY 1;", - oid); + printfPQExpBuffer(&buf, "/* %s */\n", + _("Get row-level policies for this table")); + appendPQExpBufferStr(&buf, "SELECT pol.polname,"); + appendPQExpBufferStr(&buf, + " pol.polpermissive,\n"); + appendPQExpBuffer(&buf, + " CASE WHEN pol.polroles = '{0}' THEN NULL ELSE pg_catalog.array_to_string(array(select rolname from pg_catalog.pg_roles where oid = any (pol.polroles) order by 1),',') END,\n" + " pg_catalog.pg_get_expr(pol.polqual, pol.polrelid),\n" + " pg_catalog.pg_get_expr(pol.polwithcheck, pol.polrelid),\n" + " CASE pol.polcmd\n" + " WHEN 'r' THEN 'SELECT'\n" + " WHEN 'a' THEN 'INSERT'\n" + " WHEN 'w' THEN 'UPDATE'\n" + " WHEN 'd' THEN 'DELETE'\n" + " END AS cmd\n" + "FROM pg_catalog.pg_policy pol\n" + "WHERE pol.polrelid = '%s' ORDER BY 1;", + oid); - result = PSQLexec(buf.data); - if (!result) - goto error_return; - else - tuples = PQntuples(result); + result = PSQLexec(buf.data); + if (!result) + goto error_return; + else + tuples = PQntuples(result); - /* - * Handle cases where RLS is enabled and there are policies, or - * there aren't policies, or RLS isn't enabled but there are - * policies - */ - if (tableinfo.rowsecurity && !tableinfo.forcerowsecurity && tuples > 0) - printTableAddFooter(&cont, _("Policies:")); + /* + * Handle cases where RLS is enabled and there are policies, or there + * aren't policies, or RLS isn't enabled but there are policies + */ + if (tableinfo.rowsecurity && !tableinfo.forcerowsecurity && tuples > 0) + printTableAddFooter(&cont, _("Policies:")); - if (tableinfo.rowsecurity && tableinfo.forcerowsecurity && tuples > 0) - printTableAddFooter(&cont, _("Policies (forced row security enabled):")); + if (tableinfo.rowsecurity && tableinfo.forcerowsecurity && tuples > 0) + printTableAddFooter(&cont, _("Policies (forced row security enabled):")); - if (tableinfo.rowsecurity && !tableinfo.forcerowsecurity && tuples == 0) - printTableAddFooter(&cont, _("Policies (row security enabled): (none)")); + if (tableinfo.rowsecurity && !tableinfo.forcerowsecurity && tuples == 0) + printTableAddFooter(&cont, _("Policies (row security enabled): (none)")); - if (tableinfo.rowsecurity && tableinfo.forcerowsecurity && tuples == 0) - printTableAddFooter(&cont, _("Policies (forced row security enabled): (none)")); + if (tableinfo.rowsecurity && tableinfo.forcerowsecurity && tuples == 0) + printTableAddFooter(&cont, _("Policies (forced row security enabled): (none)")); - if (!tableinfo.rowsecurity && tuples > 0) - printTableAddFooter(&cont, _("Policies (row security disabled):")); + if (!tableinfo.rowsecurity && tuples > 0) + printTableAddFooter(&cont, _("Policies (row security disabled):")); - /* Might be an empty set - that's ok */ - for (i = 0; i < tuples; i++) - { - printfPQExpBuffer(&buf, " POLICY \"%s\"", - PQgetvalue(result, i, 0)); + /* Might be an empty set - that's ok */ + for (i = 0; i < tuples; i++) + { + printfPQExpBuffer(&buf, " POLICY \"%s\"", + PQgetvalue(result, i, 0)); - if (*(PQgetvalue(result, i, 1)) == 'f') - appendPQExpBufferStr(&buf, " AS RESTRICTIVE"); + if (*(PQgetvalue(result, i, 1)) == 'f') + appendPQExpBufferStr(&buf, " AS RESTRICTIVE"); - if (!PQgetisnull(result, i, 5)) - appendPQExpBuffer(&buf, " FOR %s", - PQgetvalue(result, i, 5)); + if (!PQgetisnull(result, i, 5)) + appendPQExpBuffer(&buf, " FOR %s", + PQgetvalue(result, i, 5)); - if (!PQgetisnull(result, i, 2)) - { - appendPQExpBuffer(&buf, "\n TO %s", - PQgetvalue(result, i, 2)); - } + if (!PQgetisnull(result, i, 2)) + { + appendPQExpBuffer(&buf, "\n TO %s", + PQgetvalue(result, i, 2)); + } - if (!PQgetisnull(result, i, 3)) - appendPQExpBuffer(&buf, "\n USING (%s)", - PQgetvalue(result, i, 3)); + if (!PQgetisnull(result, i, 3)) + appendPQExpBuffer(&buf, "\n USING (%s)", + PQgetvalue(result, i, 3)); - if (!PQgetisnull(result, i, 4)) - appendPQExpBuffer(&buf, "\n WITH CHECK (%s)", - PQgetvalue(result, i, 4)); + if (!PQgetisnull(result, i, 4)) + appendPQExpBuffer(&buf, "\n WITH CHECK (%s)", + PQgetvalue(result, i, 4)); - printTableAddFooter(&cont, buf.data); - } - PQclear(result); + printTableAddFooter(&cont, buf.data); + } + PQclear(result); /* print any extended statistics */ if (pset.sversion >= 140000) @@ -3025,115 +3024,115 @@ describeOneTableDetails(const char *schemaname, } /* print any publications */ - printfPQExpBuffer(&buf, "/* %s */\n", - _("Get publications that publish this table")); - if (pset.sversion >= 150000) + printfPQExpBuffer(&buf, "/* %s */\n", + _("Get publications that publish this table")); + if (pset.sversion >= 150000) + { + appendPQExpBuffer(&buf, + "SELECT pubname\n" + " , NULL\n" + " , NULL\n" + "FROM pg_catalog.pg_publication p\n" + " JOIN pg_catalog.pg_publication_namespace pn ON p.oid = pn.pnpubid\n" + " JOIN pg_catalog.pg_class pc ON pc.relnamespace = pn.pnnspid\n" + "WHERE pc.oid ='%s' and pg_catalog.pg_relation_is_publishable('%s')\n" + "UNION\n" + "SELECT pubname\n" + " , pg_get_expr(pr.prqual, c.oid)\n" + " , (CASE WHEN pr.prattrs IS NOT NULL THEN\n" + " (SELECT string_agg(attname, ', ')\n" + " FROM pg_catalog.generate_series(0, pg_catalog.array_upper(pr.prattrs::pg_catalog.int2[], 1)) s,\n" + " pg_catalog.pg_attribute\n" + " WHERE attrelid = pr.prrelid AND attnum = prattrs[s])\n" + " ELSE NULL END) " + "FROM pg_catalog.pg_publication p\n" + " JOIN pg_catalog.pg_publication_rel pr ON p.oid = pr.prpubid\n" + " JOIN pg_catalog.pg_class c ON c.oid = pr.prrelid\n" + "WHERE pr.prrelid = '%s'\n", + oid, oid, oid); + + if (pset.sversion >= 190000) { + /* + * Skip entries where this relation appears in the + * publication's EXCEPT list. + */ appendPQExpBuffer(&buf, + " AND NOT pr.prexcept\n" + "UNION\n" "SELECT pubname\n" " , NULL\n" " , NULL\n" "FROM pg_catalog.pg_publication p\n" - " JOIN pg_catalog.pg_publication_namespace pn ON p.oid = pn.pnpubid\n" - " JOIN pg_catalog.pg_class pc ON pc.relnamespace = pn.pnnspid\n" - "WHERE pc.oid ='%s' and pg_catalog.pg_relation_is_publishable('%s')\n" - "UNION\n" - "SELECT pubname\n" - " , pg_get_expr(pr.prqual, c.oid)\n" - " , (CASE WHEN pr.prattrs IS NOT NULL THEN\n" - " (SELECT string_agg(attname, ', ')\n" - " FROM pg_catalog.generate_series(0, pg_catalog.array_upper(pr.prattrs::pg_catalog.int2[], 1)) s,\n" - " pg_catalog.pg_attribute\n" - " WHERE attrelid = pr.prrelid AND attnum = prattrs[s])\n" - " ELSE NULL END) " - "FROM pg_catalog.pg_publication p\n" - " JOIN pg_catalog.pg_publication_rel pr ON p.oid = pr.prpubid\n" - " JOIN pg_catalog.pg_class c ON c.oid = pr.prrelid\n" - "WHERE pr.prrelid = '%s'\n", + "WHERE p.puballtables AND pg_catalog.pg_relation_is_publishable('%s')\n" + " AND NOT EXISTS (\n" + " SELECT 1\n" + " FROM pg_catalog.pg_publication_rel pr\n" + " WHERE pr.prpubid = p.oid AND\n" + " (pr.prrelid = '%s' OR pr.prrelid = pg_catalog.pg_partition_root('%s')))\n" + "ORDER BY 1;", oid, oid, oid); - - if (pset.sversion >= 190000) - { - /* - * Skip entries where this relation appears in the - * publication's EXCEPT list. - */ - appendPQExpBuffer(&buf, - " AND NOT pr.prexcept\n" - "UNION\n" - "SELECT pubname\n" - " , NULL\n" - " , NULL\n" - "FROM pg_catalog.pg_publication p\n" - "WHERE p.puballtables AND pg_catalog.pg_relation_is_publishable('%s')\n" - " AND NOT EXISTS (\n" - " SELECT 1\n" - " FROM pg_catalog.pg_publication_rel pr\n" - " WHERE pr.prpubid = p.oid AND\n" - " (pr.prrelid = '%s' OR pr.prrelid = pg_catalog.pg_partition_root('%s')))\n" - "ORDER BY 1;", - oid, oid, oid); - } - else - { - appendPQExpBuffer(&buf, - "UNION\n" - "SELECT pubname\n" - " , NULL\n" - " , NULL\n" - "FROM pg_catalog.pg_publication p\n" - "WHERE p.puballtables AND pg_catalog.pg_relation_is_publishable('%s')\n" - "ORDER BY 1;", - oid); - } } else { appendPQExpBuffer(&buf, + "UNION\n" "SELECT pubname\n" - " , NULL\n" - " , NULL\n" - "FROM pg_catalog.pg_publication p\n" - "JOIN pg_catalog.pg_publication_rel pr ON p.oid = pr.prpubid\n" - "WHERE pr.prrelid = '%s'\n" - "UNION ALL\n" - "SELECT pubname\n" - " , NULL\n" - " , NULL\n" + " , NULL\n" + " , NULL\n" "FROM pg_catalog.pg_publication p\n" "WHERE p.puballtables AND pg_catalog.pg_relation_is_publishable('%s')\n" "ORDER BY 1;", - oid, oid); + oid); } + } + else + { + appendPQExpBuffer(&buf, + "SELECT pubname\n" + " , NULL\n" + " , NULL\n" + "FROM pg_catalog.pg_publication p\n" + "JOIN pg_catalog.pg_publication_rel pr ON p.oid = pr.prpubid\n" + "WHERE pr.prrelid = '%s'\n" + "UNION ALL\n" + "SELECT pubname\n" + " , NULL\n" + " , NULL\n" + "FROM pg_catalog.pg_publication p\n" + "WHERE p.puballtables AND pg_catalog.pg_relation_is_publishable('%s')\n" + "ORDER BY 1;", + oid, oid); + } - result = PSQLexec(buf.data); - if (!result) - goto error_return; - else - tuples = PQntuples(result); + result = PSQLexec(buf.data); + if (!result) + goto error_return; + else + tuples = PQntuples(result); - if (tuples > 0) - printTableAddFooter(&cont, _("Included in publications:")); + if (tuples > 0) + printTableAddFooter(&cont, _("Included in publications:")); - /* Might be an empty set - that's ok */ - for (i = 0; i < tuples; i++) - { - printfPQExpBuffer(&buf, " \"%s\"", - PQgetvalue(result, i, 0)); + /* Might be an empty set - that's ok */ + for (i = 0; i < tuples; i++) + { + printfPQExpBuffer(&buf, " \"%s\"", + PQgetvalue(result, i, 0)); - /* column list (if any) */ - if (!PQgetisnull(result, i, 2)) - appendPQExpBuffer(&buf, " (%s)", - PQgetvalue(result, i, 2)); + /* column list (if any) */ + if (!PQgetisnull(result, i, 2)) + appendPQExpBuffer(&buf, " (%s)", + PQgetvalue(result, i, 2)); - /* row filter (if any) */ - if (!PQgetisnull(result, i, 1)) - appendPQExpBuffer(&buf, " WHERE %s", - PQgetvalue(result, i, 1)); + /* row filter (if any) */ + if (!PQgetisnull(result, i, 1)) + appendPQExpBuffer(&buf, " WHERE %s", + PQgetvalue(result, i, 1)); - printTableAddFooter(&cont, buf.data); - } - PQclear(result); + printTableAddFooter(&cont, buf.data); + } + PQclear(result); /* Print publications where the table is in the EXCEPT clause */ if (pset.sversion >= 190000) @@ -3805,7 +3804,7 @@ describeRoles(const char *pattern, bool verbose, bool showSystem) ncols++; } appendPQExpBufferStr(&buf, "\n, r.rolreplication"); - appendPQExpBufferStr(&buf, "\n, r.rolbypassrls"); + appendPQExpBufferStr(&buf, "\n, r.rolbypassrls"); appendPQExpBufferStr(&buf, "\nFROM pg_catalog.pg_roles r\n"); @@ -3860,8 +3859,8 @@ describeRoles(const char *pattern, bool verbose, bool showSystem) if (strcmp(PQgetvalue(res, i, (verbose ? 9 : 8)), "t") == 0) add_role_attribute(&buf, _("Replication")); - if (strcmp(PQgetvalue(res, i, (verbose ? 10 : 9)), "t") == 0) - add_role_attribute(&buf, _("Bypass RLS")); + if (strcmp(PQgetvalue(res, i, (verbose ? 10 : 9)), "t") == 0) + add_role_attribute(&buf, _("Bypass RLS")); conns = atoi(PQgetvalue(res, i, 6)); if (conns >= 0) @@ -5155,14 +5154,14 @@ listCollations(const char *pattern, bool verbose, bool showSystem) gettext_noop("Schema"), gettext_noop("Name")); - appendPQExpBuffer(&buf, - " CASE c.collprovider " - "WHEN " CppAsString2(COLLPROVIDER_DEFAULT) " THEN 'default' " - "WHEN " CppAsString2(COLLPROVIDER_BUILTIN) " THEN 'builtin' " - "WHEN " CppAsString2(COLLPROVIDER_LIBC) " THEN 'libc' " - "WHEN " CppAsString2(COLLPROVIDER_ICU) " THEN 'icu' " - "END AS \"%s\",\n", - gettext_noop("Provider")); + appendPQExpBuffer(&buf, + " CASE c.collprovider " + "WHEN " CppAsString2(COLLPROVIDER_DEFAULT) " THEN 'default' " + "WHEN " CppAsString2(COLLPROVIDER_BUILTIN) " THEN 'builtin' " + "WHEN " CppAsString2(COLLPROVIDER_LIBC) " THEN 'libc' " + "WHEN " CppAsString2(COLLPROVIDER_ICU) " THEN 'icu' " + "END AS \"%s\",\n", + gettext_noop("Provider")); appendPQExpBuffer(&buf, " c.collcollate AS \"%s\",\n" -- 2.50.1 (Apple Git-155) --6vzYk1swa63ey9i6-- ^ permalink raw reply [nested|flat] 181+ messages in thread
end of thread, other threads:[~2026-05-06 21:43 UTC | newest] Thread overview: 181+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2021-04-04 00:24 [PATCH 4/4] Change force_parallel_mode to a DEVELOPER GUC, and remove it from sample config.. Justin Pryzby <[email protected]> 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 <[email protected]> 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 <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan 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protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2025-10-20 05:29 [PATCH v8] using indexscan to speedup add not null constraints jian he <[email protected]> 2026-05-06 21:43 [PATCH v3 4/4] run pgindent Nathan Bossart <[email protected]>
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